This invention relates to ion exchange reactors and, more particularly, to an ion exchange reactor having low pressure loss and a variable ion removal rate.
Conventional ion exchange reactors are used to remove ions from a fluid, such as water, to maintain electric resistivity, neutral pH, or both. Typical ion exchange reactors circulate fluid through a container filled with closely packed ion exchange media. The close packing of the media produces tortuous flow paths for the fluid as it flows between the media particles. The tortuous flow paths maximize the exposure of the fluid to ionically active surfaces of the media and minimize a diffusion distance that the ions must travel through the water to the ionically active surfaces. In this manner, conventional ion exchange reactors efficiently remove essentially all of the ions from the fluid in one pass through the reactor.
Although effective for ion removal, conventional ion exchange reactors that utilize packed ion exchange media have the disadvantage that the tortuous paths slow the velocity of the fluid and thereby cause a significant pressure drop between incoming fluid and outgoing fluid. The pressure drop can be overcome in part by using a larger, more powerful pump to move the fluid through the reactor. However, using a larger pump adds size and expense to the system. Further, since conventional reactors essentially remove all of the ions, control over the electric resistivity or pH of the fluid is limited.
Accordingly, there is a need for an ion exchange reactor that provides control over ion removal, and in turn over electric resistivity and pH, while achieving a relatively low pressure drop.